Another commentary by a Shenzhen University researcher, published by the China Daily, said the central government should deal with Hong Kong issues more decisively.
However, Chinese state media has stopped short of calling for military action to deal with the protests.
Five people were detained in the latest disturbances, police said, bringing the number of those arrested since the protests began in June to more than 600.
By early Wednesday, most protesters had left and many flights were operating as scheduled in the morning.
However, it was unclear if the protesters, who have no public leaders and organise via social media, would return to the airport.
The Airport Authority has obtained an injunction to remove demonstrators but enforcing it may prove difficult, as the hub is designed to make entry as fast and efficient as possible.
The Chinese government has repeatedly signalled the protesters are reaching the limits of the “one country, two systems” legal framework that gives Hong Kong its autonomy.
Authorities in Beijing on Monday described some of the violence as “terrorism”, and state-run media this week began promoting videos showing security forces gathering in Shenzhen just across the border from Hong Kong.
Mr Trump on Tuesday said his intelligence had confirmed Chinese troops were gathering across the border.
“I hope it works out for everybody including China. I hope it works out peacefully, nobody gets hurt, nobody gets killed,” he said.